#include "postgres.h"
#include "executor/spi.h"

#include "query_util.h"

MemoryContext AggregateContext = NULL;

static int
addone(int * counters, int last, int total) {
	counters[last]++;
	if ( counters[last]>=total ) {
		if (last==0)
			return 0;
		if ( addone( counters, last-1, total-1 ) == 0 )
			return 0;
		counters[last] = counters[last-1]+1;
	}
	return 1;
}

static QTNode * 
findeq(QTNode *node, QTNode *ex, MemoryType memtype, QTNode *subs, bool *isfind) {
	
	if ( (node->sign & ex->sign) != ex->sign || node->valnode->type != ex->valnode->type || node->valnode->val != ex->valnode->val )
		return node;

	if ( node->flags & QTN_NOCHANGE )
		return node;	

	if ( node->valnode->type==OPR ) {
		if ( node->nchild == ex->nchild ) {
			if ( QTNEq( node, ex ) ) {
				QTNFree( node );
				if ( subs ) {
					node = QTNCopy( subs, memtype );
					node->flags |= QTN_NOCHANGE;
				} else 
					node = NULL; 
				*isfind = true;
			}
		} else if ( node->nchild > ex->nchild ) {
			int *counters = (int*)palloc( sizeof(int) * node->nchild );
			int i;
			QTNode	*tnode = (QTNode*)MEMALLOC( memtype, sizeof(QTNode) );

			memset(tnode, 0, sizeof(QTNode));
			tnode->child = (QTNode**)MEMALLOC( memtype, sizeof(QTNode*) * ex->nchild );
			tnode->nchild = ex->nchild;
			tnode->valnode = (ITEM*)MEMALLOC( memtype, sizeof(ITEM) );
			*(tnode->valnode) = *(ex->valnode);

			for(i=0;i<ex->nchild;i++)
				counters[i]=i;

			do {
				tnode->sign=0;
				for(i=0;i<ex->nchild;i++) {
					tnode->child[i] = node->child[ counters[i] ];
					tnode->sign |= tnode->child[i]->sign;
				}

				if ( QTNEq( tnode, ex ) ) {
					int j=0;

					MEMFREE( memtype, tnode->valnode );
					MEMFREE( memtype, tnode->child );
					MEMFREE( memtype, tnode );
					if ( subs ) { 
						tnode = QTNCopy( subs, memtype );
						tnode->flags = QTN_NOCHANGE | QTN_NEEDFREE;
					} else 
						tnode = NULL;

					node->child[ counters[0] ] = tnode;

					for(i=1;i<ex->nchild;i++)
						node->child[ counters[i] ] = NULL;
					for(i=0;i<node->nchild;i++) {
						if ( node->child[i] ) {
							node->child[j] = node->child[i];
							j++;
						}
					}

					node->nchild = j;	

					*isfind = true;

					break;
				}
			} while (addone(counters,ex->nchild-1,node->nchild));
			if ( tnode && (tnode->flags & QTN_NOCHANGE) == 0 ) {
				MEMFREE( memtype, tnode->valnode );
				MEMFREE( memtype, tnode->child );
				MEMFREE( memtype, tnode );
			} else
				QTNSort( node ); 
			pfree( counters );
		}
	} else if ( QTNEq( node, ex ) ) {
		QTNFree( node );
		if ( subs ) {
			node = QTNCopy( subs, memtype );
			node->flags |= QTN_NOCHANGE;
		} else {
			node = NULL;
		}
		*isfind = true;
	}

	return node;
} 

static QTNode *
dofindsubquery( QTNode *root, QTNode *ex, MemoryType memtype, QTNode *subs, bool *isfind ) {
	root = findeq( root, ex, memtype, subs, isfind );

	if ( root && (root->flags & QTN_NOCHANGE) == 0 && root->valnode->type==OPR) {
		int i;
		for(i=0;i<root->nchild;i++)
			root->child[i] = dofindsubquery( root->child[i], ex, memtype, subs, isfind );
	}

	return root;
}

static QTNode *
dropvoidsubtree( QTNode *root ) {

	if ( !root )
		return NULL;

	if ( root->valnode->type==OPR ) {
		int i,j=0;

		for(i=0;i<root->nchild;i++) {
			if ( root->child[i] ) {
				root->child[j] = root->child[i];
				j++;
			}
		}

		root->nchild = j;

		if (  root->valnode->val == (int4)'!' && root->nchild==0 ) {
			QTNFree(root);
			root=NULL;
		} else if ( root->nchild==1 ) {
			QTNode *nroot = root->child[0];
			pfree(root);
			root = nroot;		
		} 
	}

	return root;
}

static QTNode *
findsubquery( QTNode *root, QTNode *ex, MemoryType memtype, QTNode *subs, bool *isfind ) {
	bool	DidFind = false;
	root = dofindsubquery( root, ex, memtype, subs, &DidFind );

	if ( !subs && DidFind ) 
		root = dropvoidsubtree( root );

	if ( isfind )
		*isfind = DidFind;

	return root;
}

static Oid      tsqOid = InvalidOid;
static void
get_tsq_Oid(void)
{
        int                     ret;
        bool            isnull;

        if ((ret = SPI_exec("select oid from pg_type where typname='tsquery'", 1)) < 0)
                /* internal error */
                elog(ERROR, "SPI_exec to get tsquery oid returns %d", ret);

        if (SPI_processed < 0)
                /* internal error */
                elog(ERROR, "There is no tsvector type");
        tsqOid = DatumGetObjectId(SPI_getbinval(SPI_tuptable->vals[0], SPI_tuptable->tupdesc, 1, &isnull));
        if (tsqOid == InvalidOid)
                /* internal error */
                elog(ERROR, "tsquery type has InvalidOid");
}


PG_FUNCTION_INFO_V1(tsquery_rewrite);
PG_FUNCTION_INFO_V1(rewrite_accum);
Datum           rewrite_accum(PG_FUNCTION_ARGS);

Datum 
rewrite_accum(PG_FUNCTION_ARGS) {
	QUERYTYPE	*acc = (QUERYTYPE *) PG_GETARG_POINTER(0);
	ArrayType	*qa = (ArrayType *) DatumGetPointer(PG_DETOAST_DATUM_COPY(PG_GETARG_DATUM(1)));
	QUERYTYPE	*q;
	QTNode		*qex, *subs = NULL, *acctree;
	bool isfind = false;

	AggregateContext = ((AggState *) fcinfo->context)->aggcontext;
	
	if (acc == NULL || PG_ARGISNULL(0)) {
		acc = (QUERYTYPE*)MEMALLOC( AggMemory, sizeof(QUERYTYPE) );
		acc->len = HDRSIZEQT;
		acc->size = 0;
	}

	if ( qa == NULL || PG_ARGISNULL(1) ) {
		PG_FREE_IF_COPY( qa, 1 );
		PG_RETURN_POINTER( acc );
	}

	if ( ARR_NDIM(qa) != 1 )
		elog(ERROR, "array must be one-dimensional, not %d dimension", ARR_NDIM(qa));

	if ( ArrayGetNItems( ARR_NDIM(qa), ARR_DIMS(qa)) != 3 )
		elog(ERROR, "array should have only three elements");

	if (tsqOid == InvalidOid) {
		SPI_connect();
		get_tsq_Oid();
		SPI_finish();
	}

	if (ARR_ELEMTYPE(qa) != tsqOid)
		elog(ERROR, "array should contain tsquery type");

	q = (QUERYTYPE*)ARR_DATA_PTR(qa);
	if ( q->size == 0 ) 
		PG_RETURN_POINTER( acc );
	
	if ( !acc->size ) {
		if ( acc->len > HDRSIZEQT )
			PG_RETURN_POINTER( acc );	
		else
			acctree = QT2QTN( GETQUERY(q), GETOPERAND(q) );
	} else 
		acctree = QT2QTN( GETQUERY(acc), GETOPERAND(acc) );

	QTNTernary( acctree );
	QTNSort( acctree );

	q = (QUERYTYPE*)( ((char*)ARR_DATA_PTR(qa)) + MAXALIGN( q->len ) );
	if ( q->size == 0 ) 
		PG_RETURN_POINTER( acc );
	qex = QT2QTN( GETQUERY(q), GETOPERAND(q) );
	QTNTernary( qex );
	QTNSort( qex );
	
	q = (QUERYTYPE*)( ((char*)q) + MAXALIGN( q->len ) );
	if ( q->size ) 
		subs = QT2QTN( GETQUERY(q), GETOPERAND(q) );

	acctree = findsubquery( acctree, qex, PlainMemory, subs, &isfind );

	if ( isfind || !acc->size ) {
		/* pfree( acc ); do not pfree(p), because nodeAgg.c will */
		if ( acctree ) {
			QTNBinary( acctree );
			acc = QTN2QT( acctree, AggMemory );
		} else {
			acc = (QUERYTYPE*)MEMALLOC( AggMemory, HDRSIZEQT*2 );
			acc->len = HDRSIZEQT * 2;
			acc->size = 0;
		}
	}

	QTNFree( qex );	
	QTNFree( subs );
	QTNFree( acctree );

	PG_RETURN_POINTER( acc );	
}

PG_FUNCTION_INFO_V1(rewrite_finish);
Datum           rewrite_finish(PG_FUNCTION_ARGS);

Datum 
rewrite_finish(PG_FUNCTION_ARGS) {
	QUERYTYPE	*acc = (QUERYTYPE *) PG_GETARG_POINTER(0);
	QUERYTYPE	*rewrited;
	
	if (acc == NULL || PG_ARGISNULL(0) || acc->size == 0 ) { 
		acc = (QUERYTYPE*)palloc(sizeof(QUERYTYPE));
		acc->len = HDRSIZEQT;
		acc->size = 0;
	}

	rewrited = (QUERYTYPE*) palloc( acc->len );
	memcpy( rewrited, acc, acc->len );
	pfree( acc );

	PG_RETURN_POINTER(rewrited);	
}

Datum           tsquery_rewrite(PG_FUNCTION_ARGS);

Datum
tsquery_rewrite(PG_FUNCTION_ARGS) {
	QUERYTYPE  *query = (QUERYTYPE *) DatumGetPointer(PG_DETOAST_DATUM_COPY(PG_GETARG_DATUM(0)));
	text       *in = PG_GETARG_TEXT_P(1);
	QUERYTYPE  *rewrited = query;
	QTNode	*tree;
	char	*buf;
	void 	*plan;
	Portal          portal;
	bool            isnull;
	int i;

	if ( query->size == 0 ) {
		PG_FREE_IF_COPY(in, 1);
		PG_RETURN_POINTER( rewrited );
	}

	tree = QT2QTN( GETQUERY(query), GETOPERAND(query) );
	QTNTernary( tree );
	QTNSort( tree );

	buf = (char*)palloc( VARSIZE(in) );
	memcpy(buf, VARDATA(in), VARSIZE(in) - VARHDRSZ);
	buf[ VARSIZE(in) - VARHDRSZ ] = '\0'; 

	SPI_connect();

	if (tsqOid == InvalidOid)
		get_tsq_Oid();

	if ((plan = SPI_prepare(buf, 0, NULL)) == NULL)
		elog(ERROR, "SPI_prepare('%s') returns NULL", buf);

	if ((portal = SPI_cursor_open(NULL, plan, NULL, NULL, false)) == NULL)
		elog(ERROR, "SPI_cursor_open('%s') returns NULL", buf);
	
	SPI_cursor_fetch(portal, true, 100);

	if (SPI_tuptable->tupdesc->natts != 2)
		elog(ERROR, "number of fields doesn't equal to 2");

	if (SPI_gettypeid(SPI_tuptable->tupdesc, 1) != tsqOid )
		elog(ERROR, "column #1 isn't of tsquery type");

	if (SPI_gettypeid(SPI_tuptable->tupdesc, 2) != tsqOid )
		elog(ERROR, "column #2 isn't of tsquery type");

	while (SPI_processed > 0 && tree ) {
		for (i = 0; i < SPI_processed && tree; i++) {
			Datum           qdata = SPI_getbinval(SPI_tuptable->vals[i], SPI_tuptable->tupdesc, 1, &isnull);
			Datum           sdata;

			if ( isnull )	continue;

			sdata = SPI_getbinval(SPI_tuptable->vals[i], SPI_tuptable->tupdesc, 2, &isnull);

			if (!isnull) {
				QUERYTYPE	*qtex = (QUERYTYPE *) DatumGetPointer(PG_DETOAST_DATUM(qdata));
				QUERYTYPE	*qtsubs = (QUERYTYPE *) DatumGetPointer(PG_DETOAST_DATUM(sdata));
				QTNode		*qex, *qsubs = NULL;

				if (qtex->size == 0) {
					if ( qtex != (QUERYTYPE *) DatumGetPointer(qdata) )
						pfree( qtex );
					if ( qtsubs != (QUERYTYPE *) DatumGetPointer(sdata) )
						pfree( qtsubs );
					continue;
				}

				qex = QT2QTN( GETQUERY(qtex), GETOPERAND(qtex) );

				QTNTernary( qex );
				QTNSort( qex );

				if ( qtsubs->size ) 
					qsubs = QT2QTN( GETQUERY(qtsubs), GETOPERAND(qtsubs) );

				tree = findsubquery( tree, qex, SPIMemory, qsubs, NULL );
				 
				QTNFree( qex );	
				if ( qtex != (QUERYTYPE *) DatumGetPointer(qdata) )
					pfree( qtex ); 
				QTNFree( qsubs );	
				if ( qtsubs != (QUERYTYPE *) DatumGetPointer(sdata) )
					pfree( qtsubs ); 
			}
		}

		SPI_freetuptable(SPI_tuptable);
		SPI_cursor_fetch(portal, true, 100);
	}
	
	SPI_freetuptable(SPI_tuptable);
	SPI_cursor_close(portal);
	SPI_freeplan(plan);
	SPI_finish();	


	if ( tree ) {
		QTNBinary( tree );
		rewrited = QTN2QT( tree, PlainMemory );
		QTNFree( tree );
		PG_FREE_IF_COPY(query, 0);
	} else {
		rewrited->len = HDRSIZEQT;
		rewrited->size = 0;
	}

	pfree(buf);
	PG_FREE_IF_COPY(in, 1);
	PG_RETURN_POINTER( rewrited ); 
}


PG_FUNCTION_INFO_V1(tsquery_rewrite_query);
Datum           tsquery_rewrite_query(PG_FUNCTION_ARGS);

Datum
tsquery_rewrite_query(PG_FUNCTION_ARGS) {
        QUERYTYPE  *query = (QUERYTYPE *) DatumGetPointer(PG_DETOAST_DATUM_COPY(PG_GETARG_DATUM(0)));
        QUERYTYPE  *ex = (QUERYTYPE *) DatumGetPointer(PG_DETOAST_DATUM(PG_GETARG_DATUM(1)));
        QUERYTYPE  *subst = (QUERYTYPE *) DatumGetPointer(PG_DETOAST_DATUM(PG_GETARG_DATUM(2)));
        QUERYTYPE  *rewrited = query;
        QTNode  *tree, *qex, *subs = NULL;

        if ( query->size == 0 || ex->size == 0 ) {
                PG_FREE_IF_COPY(ex, 1);
                PG_FREE_IF_COPY(subst, 2);
                PG_RETURN_POINTER( rewrited );
        }

        tree = QT2QTN( GETQUERY(query), GETOPERAND(query) );
        QTNTernary( tree );
        QTNSort( tree );

        qex = QT2QTN( GETQUERY(ex), GETOPERAND(ex) );
        QTNTernary( qex );
        QTNSort( qex );

	if ( subst->size ) 
        	subs = QT2QTN( GETQUERY(subst), GETOPERAND(subst) );

        tree = findsubquery( tree, qex, PlainMemory, subs, NULL );
        QTNFree( qex );
        QTNFree( subs );

	if ( !tree ) {
		rewrited->len = HDRSIZEQT;
		rewrited->size = 0;
                PG_FREE_IF_COPY(ex, 1);
                PG_FREE_IF_COPY(subst, 2);
                PG_RETURN_POINTER( rewrited );
	} else {
        	QTNBinary( tree );
        	rewrited = QTN2QT( tree, PlainMemory );
        	QTNFree( tree );
	}

        PG_FREE_IF_COPY(query, 0);
        PG_FREE_IF_COPY(ex, 1);
        PG_FREE_IF_COPY(subst, 2);
        PG_RETURN_POINTER( rewrited );
}